The present invention concerns a method of and a device for buffering sheets of cut stock in block-shaped stacks ranged in rows between stock-cutting machinery and further-processing machinery.
A method of and a device for cutting stacked sheets of paper, cardboard, plastic, etc., especially sheet assemblages, is known from German A 3 101 911. The device is a guillotine. To ensure that the blade always cuts the stack along the intended line, the stack must be advanced below the blade very precisely. Even slight displacements, dimensional deviations due to curling paper for instance, can force the blade to cut the paper away from the intended line. Assemblages especially, with a number of labels printed on them, can accordingly be cut inside the print. To prevent this malfunction the sheets are printed with the separate printed matter not immediately mutually adjacent but with empty passages left between them. It is accordingly admittedly necessary to make additional cuts between the main cuts, although the procedure does prevent cutting into the printed matter. The stacks can also be trimmed at their margins before they are cut. The advantage of this approach is that, once the margins have been trimmed, the stack will be in a prescribed shape or format, a decisive feature for ensuring the accuracy of the following major cut. When labels are cut, the margin-trimmed block-shaped stack is initially cut parallel to the main cut and then parallel to any intermediate cuts and rotated 90.degree. to allow main cuts and intermediate cuts if any to be made perpendicular to the original cuts. Subsequent to every 90.degree. rotation, accordingly, every main cut will leave a row of smaller block-shaped stacks adjacent parallelling the blade, every row itself being block-shaped. The smaller stacks are forwarded to further-processing machinery, where they are punched or bundled for example.
From the processing steps hereintofore described it will be evident that the stock will necessarily leave the stock-cutting machinery discontinuously. It will accordingly take several minutes, two or three for instance, to make the marginal cuts and to cut the main stack into strips. During this time, no cut stock can be forwarded to the further-processing machinery. The further processing machinery, however, could easily handle the smaller stacks, bundling them or punching out irregularly shaped labels and then bundling them.
Every row of smaller stacks produced by the guillotine described in German A 3 101 911 must be removed from the vicinity of the blade manually and transferred to an adjacent counter, whence they can be forwarded manually to the further-processing machinery.
Stock-cutting machinery with two guillotines is known from European A 0 242 763. The downstream guillotine generates the rows of stacks, and a pusher removes them longitudinally. In practice, the pusher transfers each row generated in this system onto an adjacent counter and hence directly to further-processing machinery, where each stack is banded.
A multiple bundler with a feed is known from German U 29 804 929. This device is employed to bundle discontinuously supplied rows of finished stacks, large-format stock in other words, and not to handle rows of smaller stacks.